Repointing historic masonry the right way - Part 1 - Clearing Mortar Joints

Summary

This video provides a detailed guide on how to remove and replace mortar in brick joints. It covers essential techniques, such as cutting the joint with a blade, using a chisel and hammer for vertical joints, and the careful removal of mortar using both manual and pneumatic chisels. The process includes cleaning the joints thoroughly, pre-wetting the wall, and ensuring proper absorption of water before applying new mortar. The video emphasizes the importance of patience and precision to avoid damaging the bricks and to ensure successful mortar replacement.

Takeaways

• 😀 Use a blade that is no wider than 1/3 of the joint to cut along the center, making multiple passes to reach the desired depth.
• 😀 Avoid using a circular blade for vertical joints, and instead, use a chisel and hammer for mortar removal.
• 😀 When using a chisel, position the blade close to the lip of the brick, but avoid touching the brick itself to prevent damage.
• 😀 Start chiseling at the bottom of vertical joints and work upward to avoid damaging the brick.
• 😀 Remove any loose mortar pieces that obstruct your work area during the chiseling process.
• 😀 A pneumatic chisel can speed up mortar removal, but be cautious to prevent damage to the bricks.
• 😀 Square-cut the back of the joint when using a pneumatic chisel to ensure proper mortar replacement.
• 😀 Use a brush to clean out any remaining mortar and dust from the joints and brick faces before proceeding with new mortar.
• 😀 Thoroughly rinse the joints and the brick face to remove any debris and dust to prepare for mortar installation.
• 😀 Pre-wet the wall several times before applying new mortar, allowing enough time for the water to absorb into the existing brick and mortar.
• 😀 Wash the wall from top to bottom during pre-wetting to avoid spreading debris to already cleaned areas and ensure proper moisture absorption.

Q & A

Why is it important to use a blade that is at most 1/3 the width of the joint when cutting mortar?

Using a blade that is 1/3 the width of the joint ensures precise cuts, reduces damage to the surrounding brickwork, and allows for better control during the cutting process.

What is the reason for not using a circular blade on vertical joints?

A circular blade can cause damage to the bricks in vertical joints. A chisel and hammer are recommended as they allow for more controlled and careful removal of mortar without damaging the brick.

How should a chisel be positioned when removing mortar from a vertical joint?

The chisel should be positioned close to the lip of the brick without actually touching it. Gently tap the chisel with a hammer to loosen the mortar.

What is the recommended starting point for chiseling vertical joints, and why?

It is recommended to start at the bottom of the joint and work your way up. This helps avoid damaging the brick, as chiseling from the top down could cause the brick to loosen or break.

What precautions should be taken when using a pneumatic chisel?

When using a pneumatic chisel, extra care must be taken to avoid damage to the bricks. It is important to control the tool's force and to use it carefully to prevent excessive impact on the brick.

How can you ensure that the back of the mortar joint is cut properly when using a pneumatic chisel?

When using a pneumatic chisel, try to square cut the back of the joint to ensure proper mortar replacement and prevent gaps or weak points when re-mortaring.

What should be done after removing the mortar from the joints?

After removing the mortar, use a brush to remove any remaining mortar pieces and dust from the joints and the horizontal lip of the bricks. This ensures the surface is clean and ready for new mortar.

Why is it important to rinse the joints and bricks after cleaning?

Rinsing the joints and bricks thoroughly removes any dust or debris that could interfere with the adhesion of the new mortar, ensuring a clean surface for better mortar bonding.

What is the purpose of rewetting the wall before mortar installation?

Rewetting the wall allows the water to soak into the existing brick and mortar, preventing them from absorbing moisture from the new mortar too quickly, which could affect the mortar’s setting and strength.

How can you tell when the joints are ready to be pointed with new mortar?

The joints are ready to be pointed when the wall has absorbed the water, and all standing water on the surface has been absorbed or drained off, leaving the surface damp but not wet.